The Light Hadron Mass Spectrum with Non-Perturbatively O(a) Improved Wilson Fermions

We compute the light hadron mass spectrum in quenched lattice QCD at $\beta = 6.0$ using the Sheikholeslami-Wohlert fermionic action. The calculation is done for several choices of the coefficient $c_{SW}$, including $c_{SW} = 0$ and the recently proposed optimal value $c_{SW} = 1.769$. We find that the individual masses change by up to 30\% under $O(a)$ improvement. The spectrum calculation suggests $c_{SW} \approx 1.4$ for the optimal value of the coefficient.Comment: 15 pages, uuencoded Z-compressed postscript file. Also available from http://www.desy.de/pub/preprints/desy/199

Universal Rights and Wrongs

This paper argues for the important role of customers as a source of competitive advantage and firm growth, an issue which has been largely neglected in the resource-based view of the firm. It conceptualizes Penrose’s (1959) notion of an ‘inside track’ and illustrates how in-depth knowledge about established customers combines with joint problem-solving activities and the rapid assimilation of new and previously unexploited skills and resources. It is suggested that the inside track represents a distinct and perhaps underestimated way of generating rents and securing long-term growth. This also implies that the sources of sustainable competitive advantage in important respects can be sought in idiosyncratic interfirm relationships rather than within the firm itself

Techniques for automatic assembly

The objective of the research work carried out was the development of techniques useful in automated assembly. In particular, methods were sought which would allow the extension of simple robot capabilities from the "pick and place" function to the less ordered domain of assembly. Three approaches towards correcting the gross misalignment of a peg and hole are described. An established method of facilitating assembly involves the vibration of the contacting misaligned components. This technique was studied with respect to the behaviour of an elastically constrained peg under the action of a rotating force. The study was limited initially to a relatively straightforward analysis of simplified situations, then, in order to allow the prediction of the behaviour of practical systems a program was developed which simulated the behaviour of a general nine degree-of-freedom assembly system. This work led to the second approach where the possibility of using the vibrational motion of the contacting components as feedback for position sensing was investigated. The third technique involved determining the spatial relationship between the components on the basis of contact forces sensed in their respective coordinate systems. Finally a six degree-of-freedom force-displacement sensor, able to be used for, either vibratory position sensing, or contact force position sensing, was developed

The three dimensional dilute Ising magnet

The dilute Ising model with a p = 0.8 fraction of the sites occupied by spins is simulated on L3 systems for L up to 300, using a single-cluster algorithm of Wolff. In the range of reduced temperature 0.002 < (T - Tc)/Tc < 0.03 the susceptibility appears to fit a simple power with an effective exponent γ eff≈ 1.36

Characterisation and comparison of the host response of 6 tissue-based surgical implants in a subcutaneous in vivo rat model

Background Hernia repair often involves fascial augmentation using biologic prostheses. Small processing changes during preparation modulate host tissue response, which influence material efficacy and longevity. In this pilot study, a rat model was used to determine the specific influence of tissue origin, decellularisation treatment and 1,6-hexamethylene diisocyanate (HMDI) cross-linking. Methods Materials (1 cm2) were implanted subcutaneously into 6-week-old Wistar rats (4 materials per animal, n=6/material per time point) for 2, 5, 7, 14 and 28 days. Histologic processing was carried out after resin infiltration, observing classical histopathology and pathologic indexing. Materials comprised 6 tissue-based grafts covering both experimental and commercial porcine decellularised dermal and small intestinal submucosal materials. Results Subcutaneous delivery of biologics demonstrated material-specific inflammatory/host responses. Controlled variations of the Permacol™ manufacturing process showed sodium dodecyl sulfate (SDS) was the most proinflammatory decellularisation reagent, and HMDI cross-linking had no effect on host response. All materials remained recoverable after 28 days, although Surgisis™ had partially resorbed. Conclusion Differences in host responses exist between biologic implants for hernia repair in this rat model. It is postulated that these modifications are induced during processing and may have an effect on the clinical outcome of hernia repair. </jats:sec